George, 40, abused young children at Little Ted's nursery where she worked in Plymouth, and Allen, from Nottingham, assaulted youngsters to please Blanchard.

Sentenced alongside Blanchard on Monday were mother-of-nine Tracy Lyons, 41, of Portsmouth, who was jailed for seven years and Tracy Dawber, 44, of Southport, who was jailed for four years.

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Vanessa George and Angela Allen admitted a string of charges of sexual assault and child pornography

Dawber was in a year-long relationship with Blanchard, unlike the other women, who had never actually met him.

George, Allen and Lyons pleaded guilty to a string of charges of sexual assault and making and possessing child pornography.

Dawber denied one count of sexually assaulting a child and five counts of permitting indecent photographs of a child to be taken, but was found guilty in October after a retrial.

Andy Pilling, from Greater Manchester Police, said the fact that women were involved in this case was "unusual".

"Sadly, we expect to see men involved in child abuse, but to see four women being led by a man and each abusing children is probably one of the rarest things that I've ever seen," he said.

"Certainly for Colin Blanchard, he has a clear sexual interest in children.

"The only thing we can say in relation to the women at the moment is that they tried to please him, that they were involved with him in either sexual fantasy or, in Tracy Dawber's case, they were involved in a relationship."